Substrate with via and pad structures

Abstract

This invention relates to a substrate with via and pad structure(s) to reduce solder wicking. Each via and pad structure connects a component to conductive layers associated with the substrate. The substrate includes one or more plated vias, solder mask(s) surrounding the plated vias, and a conductive pad with a conductive trace connected to each plated via. The conductive pad extends beyond the terminal sides to increase solder formation and the solder mask reduces solder formation at the terminal end of the component. The via and pad structure is suitable for a variety of components and high component density. The invention also provides a computer implemented method for calculating the maximum distance of a conductive pad extending beyond the terminal side of a component.

1. A substrate with a via and pad structure connecting a surface mount component to conductive layers of the substrate, comprising:
 a surface mount component, wherein the surface mount component includes a package having an upper surface with solderable terminal sides and a terminal end; 
 a substrate; 
 a plated via connected to the conductive layers; 
 a solder mask surrounding the plated via; and 
 a conductive pad with a conductive trace connected to the plated via, wherein the solder mask exposes a part of the conductive pad that extends beyond the solderable terminal sides of the surface mount component to increase solder formation between the conductive pad and the solderable terminal sides and to reduce solder formation at the first plated via, wherein the solder mask covers a part of the conductive pad that extends beyond the solderable terminal end and reduces solder formation at the terminal end of the surface mount component. 
 
     
     
       2. The substrate with the via and pad structure of  claim 1 , wherein the conductive pad includes a first arm and a second arm that extend beyond the solderable terminal sides of the surface mount component. 
     
     
       3. The substrate with the via and pad structure of  claim 1 , wherein the conductive pad includes a first arm, a second arm, and a body. 
     
     
       4. The substrate with the via and pad structure of  claim 1 , wherein the conductive pad includes a T-shirt shaped structure. 
     
     
       5. The substrate with the via and pad structure of  claim 1 , wherein the solder mask is keyhole shaped. 
     
     
       6. The substrate with the via and pad structure of  claim 1 , wherein the solder mask covers the substrate partially or entirely except the conductive pad and the plated via. 
     
     
       7. The substrate with the via and pad structure of  claim 1 , further comprising solder joint(s), wherein the solder joints have a greater volume at the solderable terminal sides than at the terminal end of the surface mount component. 
     
     
       8. The substrate with the via and pad structure of  claim 1 , wherein the substrate is part of a printed circuit board. 
     
     
       9. The substrate with the via and pad structure of  claim 1 , wherein the substrate is part of a BGA package footprint. 
     
     
       10. The substrate with the via and pad structure of  claim 1 , wherein solder mask is a ring surrounding the plated via. 
     
     
       11. The substrate with the via and pad structure of  claim 2 , wherein the first arm and the second arm are symmetrically disposed on the substrate with respect to the plated via. 
     
     
       12. The substrate with the via and pad structure of  claim 3 , wherein the first arm and the second arm are symmetrically disposed on the substrate with respect to the plated via. 
     
     
       13. The substrate with the via and pad structure of  claim 4 , wherein the T-shirt shaped structure is symmetrically disposed on the substrate with respect to the plated via. 
     
     
       14. A substrate with a plurality of via and pad structures connecting a surface mount component to conductive layers of the substrate, comprising:
 a surface mount component, wherein the surface mount component includes a package having an upper surface with first solderable terminal sides and a first terminal end and second solderable terminal sides and a second terminal end; 
 a substrate; 
 a first plated via connected to the conductive layers; 
 a first solder mask surrounding the first plated via; 
 a second plated via connected to an associated conductive layer; 
 a second solder mask surrounding the second plated via; 
 a first conductive pad with a conductive trace connected to the first plated via, wherein the first conductive pad includes a portion that is exposed to solder and extends beyond the first solderable terminal sides of the surface mount component to increase solder formation along the first solderable terminal sides and to reduce solder formation at the first plated via; and 
 a second conductive pad with a conductive trace connected to the second plated via, wherein the second conductive pad includes a portion that is exposed to solder end extends beyond the second solderable terminal sides of the surface mount component to increase solder formation along the second solderable terminal sides and to reduce solder formation at the second plated via, wherein the first solder mask covers and reduces solder formation at the first terminal end of the surface mount component and the second solder mask covers and reduces solder formation at the second terminal end of the surface mount component. 
 
     
     
       15. The substrate with the plurality of via and pad structures of  claim 14 , wherein each of the first and second conductive pads include a first arm and a second arm. 
     
     
       16. The substrate with the plurality of via and pad structures of  claim 14 , wherein the first and second conductive pads include a first arm, a second arm, and a body. 
     
     
       17. The substrate with the plurality of via and pad structures of  claim 14 , wherein each of the first and second conductive pads include a T-shirt shaped structure. 
     
     
       18. The substrate with the plurality of via and pad structures of  claim 14 , wherein each of the first and second solder masks is a ring surrounding the first and second plated vias, respectively. 
     
     
       19. The substrate with the plurality of via and pad structures of  claim 14 , wherein each of the first and second solder masks is a keyhole shape and surrounds the first and second plated vias, respectively. 
     
     
       20. The substrate with the plurality of via and pad structures of  claim 14 , wherein each of the first and second solder masks cover the substrate partially or entirely except the first and second conductive pads and the first and second plated vias. 
     
     
       21. The substrate with the plurality of via and pad structures of  claim 14 , further comprising solder joint(s), wherein the solder joint(s) have a greater volume at each of the solderable terminal sides than at each terminal end of the surface mount component. 
     
     
       22. The substrata with the plurality of via and pad structures of  claim 14 , wherein the separation along the substrate between the first and second solder masks defines the length of the surface mount component to be soldered. 
     
     
       23. The substrate with the plurality of via and pad structures of  claim 14 , wherein the substrate is part of a printed circuit board. 
     
     
       24. The substrate with the plurality of via and pad structures of  claim 14 , wherein the substrate is part of a BGA package footprint. 
     
     
       25. The substrate with the plurality of via and pad structures of  claim 14 , wherein the first conductive pad extends beyond the terminal side of the component at a distance that reduces solder wicking without generating electrical shorts between the first conductive pad and an adjacent plated via. 
     
     
       26. The substrate with the plurality of via and pad structures of  claim 15 , wherein each of the first and second conductive pads is symmetric to the first plated via and the second plated vias, respectively. 
     
     
       27. The substrate with the plurality of via and pad structures of  claim 16 , wherein each of the first and second conductive pads is symmetric to the first plated via and the second plated vias, respectively. 
     
     
       28. The substrate with the plurality of via and pad structures of  claim 17 , wherein each of the T-shirt shaped structures is symmetric to the first and second plated vias, respectively.